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671.
We analyzed the possible effects of grazing management and future climate change on carbon (C) stocks in soils of northern
Patagonian shrublands. To this aim, we coupled the outputs of three (HadCM3, CSIRO Mk2, and CCSR/NIES) global climate models
to the CENTURY (v5.3) model of terrestrial C balance. The CENTURY model was initialized with long-term field data on local
biome physiognomy, seasonal phenologic trends, and prevailing land-management systems and was validated with recent sequences
of 1-km Normalized Difference Vegetation Index (MODIS-Terra) images and soil C data. In the tested scenarios, the predicted
climate changes would result in increased total C in soil organic matter (SOMTC). Maximum SOMTC under changed climate forcing
would not differ significantly from that expected under baseline conditions (8 kg m−2). A decrease in grazing intensity would result in SOMTC increases of 11% to 12% even if climate changes did not occur. Climate
change would account for SOMTC increases of 5% to 6%. 相似文献
672.
Frank Huess Hedlund 《Safety Science》2012,50(3):537-553
Carbon dioxide is an asphyxiant and an irritant gas. An extreme outburst of carbon dioxide took place 7 July 1953 in a potash mine in the former East Germany. During 25 min, a large amount of CO2 was blown out of the mine shaft with great force. It was wind still and concentrated CO2 accumulated in a valley leading to multiple asphyxiation casualties. Based on a review of concentration-response relationships, the location of victims, and other information, it is concluded that concentrations of 10-30% carbon dioxide may have occurred 450 m from the point of release for at least 45 min. It is concluded that 1100-3900 tonnes of CO2 were blown out of the mine shaft, possibly with intensities around 4 tonnes/s. It is also concluded that the large majority of the gas escaped as a near-vertical high-velocity jet with only little loss of momentum due to impingement. The release was modelled using PHAST. Output from the model is inconsistent with the asphyxiation harm observed. The high-momentum release is predicted to disperse safely and never reach the ground. Carbon dioxide capture and storage (CCS) schemes will involve handling and transportation of unprecedented quantities of CO2. Case histories to date include sudden releases of CO2 of up to 50 tonnes only, far too small to provide a suitable empirical perspective on predicted hazard distances for CCS projects. The 1953 outburst contributes to filling this gap. 相似文献
673.
笔者研究了快速监测一氧化碳气体的新方法即一氧化碳被动式检气管法。该方法基于气体分子扩散定律和化学吸收反应原理。检气管内的惰性载体涂渍上对一氧化碳有特效的显色剂:氯化钯—稳定剂G-浓硫酸体系。一氧化碳通过检气管端口扩散进入管内,与惰性载体上的显色剂发生反应,从而产生颜色变化。检气管显色长度的平方与一氧化碳浓度及采样时间的乘积在80~800mg/m3范围内(采样一小时)成线性关系,从而求出环境中一氧化碳的时间加权平均浓度。该检气管集采样与分析为一体,可快速测定一氧化碳气体的浓度。经过应用实验表明,该检气管具有较高的灵敏度,基本上达到设计要求。 相似文献
674.
非盒属材料的荧光紫外灯曝露试验概述 总被引:1,自引:0,他引:1
荧光紫外灯曝露试验是非金属材料的人工气候老化试验的常用方法,本文着重介绍了荧光紫外灯曝露试验的原理、荧光紫外灯曝露试验设备的要求、主要的荧光紫外灯试验标准以及荧光紫外灯曝露试验应考虑的因素. 相似文献
675.
Degradative solidification/stabilization (DS/S) is a novel remediation technology that combines chemical degradation with conventional solidification/stabilization. The applicability of the Fe(II)-based DS/S to treating chlorinated alkanes was tested by characterizing degradation reactions of carbon tetrachloride (CT) and its daughter products in cement slurries containing Fe(II). Degradation kinetics of CT and chloroform (CF) were generally very rapid with reaction rates comparable to rates that can be obtained with zero-valent iron. Dechlorination reactions of CT proceeded primarily via a hydrogenolysis pathway, which yielded CF and methylene chloride (MC) as major products and chloromethane and methane as minor products. However, reaction pathways other than hydrogenolysis also appeared to be important at very high pH conditions. MC apparently was resistant to dechlorination reactions over a period of about two months. Kinetics of CT and CF transformation were strongly dependent on pH with an optimal value around 13, which was higher than found previously for PCE. When the initial CF concentration varied between 0.01 and 1 mM, and the Fe(II) dose was 104 mM, pseudo-first-order kinetics generally described the degradation reactions of CF. However, there was also some indication of substrate saturation kinetics in these experiments. This suggests that a saturation model would better describe the kinetics in systems with higher concentration of substrates or lower concentration of the reactive surfaces. 相似文献
676.
The paper presents a generic computer model for estimating short-term steady-state fluxes of CO2, water vapor, and heat from broad leaves and needle-leaved coniferous shoots of C3 plant species. The model explicitly couples all major processes and feedbacks known to impact leaf biochemistry and biophysics including biochemical reactions, stomatal function, and leaf-boundary layer heat- and mass-transport mechanisms. The ability of the model to successfully predict measured photosynthesis and stomatal-conductance data as well as to simulate a variety of observed leaf responses is demonstrated. A model application investigating physiological and environmental regulation of leaf water-use efficiency (WUE) under steady-state conditions is discussed. Simulation results suggest that leaf physiology has a significant control over the environmental sensitivity of leaf WUE. The implementation of a highly efficient solution technique allows the model to be directly incorporated into plant-canopy and terrestrial ecosystem models. 相似文献
677.
The ASTM D5210-91 protocol for evaluating the biodegradability of a polymer was examined. The reactor design was modified not only to account for the total CO2 evolved but also to allow for the simultaneous carbon assessment in microbes, soluble products, and solid samples. Improvements in the test procedure were implemented such as (1) refining the CO2 pretrap and posttrap design, (2) optimizing the carbon dioxide removal efficiency, (3) accounting for the total polymeric carbon, (4) standardizing the inoculum, and (5) revising the nutrient medium. By growing the sludge on a suitable substrate prior to polymeric exposure, a constant microbial density was obtained. The modified ASTM method provides an assessment of the polymeric carbon degradation at any given time. The results of this work have specific significance to the behavior of polymers in a sewage waste treatment plant, where sludge is continuously being acrated, and also for aerobic biodegradation in general. 相似文献
678.
Carbon dioxide emission reduction scenarios for Finland are compared with respect to the radiative forcing they cause (heating
power due to the absorption of infrared radiation in the atmosphere). Calculations are made with the REFUGE system model using
three carbon cycle models to obtain an uncertainity band for the development of the atmospheric concentration.
The future emissions from the use of fossil fuels in Finland are described with three scenarios. In the reference scenario
(business-as-usual), the emissions and the radiative forcing they cause would grow continuously. In the scenario of moderate
emission reduction, the emissions would decrease annually by 1% from the first half of the next century. The radiative forcing
would hardly decrease during the next century, however. In the scenario of strict emission reductions, the emissions are assumed
to decrease annually by 3%, but the forcing would not decrease until approximately from the middle of the next century depending
on the model used. Still, in the year 2100 the forcing would be considerably higher than the forcing in 1990. Due to the slow
removal of CO2 from the atmosphere by the oceans, it is difficult to reach a decreasing radiative forcing only by limiting fossil CO2 emissions.
The CO2 emissions from fossil fuels in Finland contribute to the global emissions presently by about 0.2%. The relative contribution
of Finnish CO2 emissions from fossil fuels to the global forcing due to CO2 emissions is presently somewhat less than 0.2% due to relatively smaller emissions in the past. The impact of the nonlinearity
of both CO2 removal from the atmosphere and of CO2 absorption of infrared radiation on the results is discussed. 相似文献
679.
ABSTRACT The calls for greater racial equity also means cleaning up the air, water, and soil. Poor people needlessly suffer more in Louisville than the same low-income people in West Coast cites. If we adopted the same tough, environmental regulations as our West Coast Counterparts West Louisville would surely bloom instead of slowly die. The unfairness between black and white neighbourhoods is stark and vivid. As the great urbanist, Jane Jacobs, once said: “everyone hungers for a first class neighbourhood for both pride and dignity?…?nobody wants a second class neighborhood.” First class neighbourhoods are safe, healthy, sustainable, and prosperous. It is a human right; a Worldwide right. 相似文献
680.
The present study centered on the composition of landfill gas and its effects on soil and plants at the Gin Drinkers' Bay (GDB) landfill in Hong Kong This first part of the study was a whole-year monitoring of landfill gas composition in the gas ventilation system installed on top of the landfill Methane, carbon dioxide, oxygen, and ethylene were measured It was shown that gas generation was positively correlated with the amount of precipitation and air temperature and negatively correlated with atmospheric pressure 相似文献